1. Field of the invention
The present invention relates to an inlet of an underground reservoir, and more particularly, to an inlet of an underground reservoir for generating a vortex in a flux (a rate of flow) lower than a design flow.
2. Description of the Related Art
Generally, inlets for flowing rain to an underground reservoir after the rain are formed at conventional drains or drainage holes of road sides.
The inlets are classified into a tangential intake structure and a spiral intake structure that are usually used for the inlets. In the inlet having the tangential intake structure, an installation space is a small and the installation process is simple when it is installed. In the inlet having the spiral intake structure, a spiral structure is formed from an inlet portion to a shaft (a vertical shaft or a mineshaft) to form a vortex inside the inlet. And thus, the vortex flow is naturally generated in the inlet having the spiral intake structure.
However, when a flux flowing into the inlet, which is for guiding the water such as rain to a conventional underground reservoir, is lower than a design flux, the vortex flow is not sufficiently formed inside the inlet. Therefore, an original function of the inlet cannot be achieved.
When the vortex flow inside the inlet does not generate, since energy of the flow does not dissipate, various problems such as damage, breakage, and so on of a structure are caused.